trans-Tetraaquabis(isonicotinamide-kappa N-1)nickel(II) bis(3-hydroxybenzoate) tetrahydrate

Abstract

The asymmetric unit of the title compound, [Ni(C6H6N2O)(2)(H2O)(4)](C7H5O3)(2)center dot 4H(2)O, contains one-half of the complex cation with the Ni-II ion located on an inversion center, a 3-hydroxybenzoate counter-anion and two uncoordinated water molecules. Four water O atoms in the equatorial plane around the Ni-II ion [Ni-O = 2.052 (2) and 2.079 (2) angstrom] form a slightly distorted square-planar arrangement, which is completed up to a distorted octahedron by the two N atoms [Ni-N = 2.075 (3) angstrom] from two isonicotinamide ligands. In the anion, the carboxylate group is twisted from the attached benzene ring by 8.8 (3)degrees. In the crystal, a three-dimensional hydrogen-bonding network, formed by classical O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds, consolidates the crystal packing, which also exhibits pi-pi interactions between the benzene and pyridine rings, with centroid-centroid distances of 3.455 (2) and 3.621 (2) angstrom, respectively.